Some opposition to the so-called Ground Zero mosque reflects concerns for those who lost family in the 9/11 attacks. But many opponents appear uncomfortable with the very idea of Islam. If their opposition succeeds, the chances of what they fear most -- more militant American Muslims -- could increase, critics say.

John Watts of Staten Island, right, protests at the proposed site for the Muslim center next to Matt Sky, left, and Julia Lundy, who support building near ground zero in New York City's financial district. The proposed Mosque at 51 Park Place, just blocks from Ground Zero, will be a center similar to a Y.M.C.A. and has caused controversy.

The increasingly acrimonious debate over the construction of the so-called Ground Zero mosque in Manhattan, about two blocks away from the World Trade Center towers that were destroyed by Al Qaeda on Sept. 11, 2001, echoes similar debates in Europe and could, if the rhetoric becomes commonplace, have broad and negative ramifications for the integration of America's growing Muslim population.

Though some opponents of the Muslim community center say they are simply worried about the feelings of 9/11 relatives, since the men who carried out the attacks were Muslims, others see the attempt to build the center in a former Burlington Coat Factory outlet as an offensive in what they view as a cultural war.

The United State's experience with its Muslim citizens, and vice versa, has been a profoundly different and more positive one than that found in most of Europe, where countries with largely homogeneous ethnic and religious identities first started to grapple with large influxes of Muslim immigrants after World War II. In Europe, Muslims are more likely to report feeling alienated from society, and tend to have fewer economic opportunities -- all of which has, on the margins, led to a greater relative number of young European Muslim men being attracted to the violent ideology espoused by Al Qaeda and its fellow travelers.